There was an OCDO BBQ at Luther Burbank in 2009 after the incident in Mercerdale Park.
I don't think Mercer would be a great place for a gun store, and definitely not for a range. It's an expensive residential area with a very small business district. Leasing costs are very high due to the limited space and there aren't many small independent retailers here, mostly banks, realtors, doctors offices etc. Small businesses struggle to survive because of the cost and the limited market - most people shopping here live here. Also, you are competing with West Coast Armory which has an excellent range and well established store just across the bridge.
MI is similar to a lot of wealthy Eastside suburbs like Medina and Kirkland - low crime, there are a lot of people with money and you'd be surprised at the number with extensive firearm collections, but they don't advertise it. I go shooting with four of my close neighbors regularly and all are pro-2A, CCW, very well armed and have memberships at WCA. I'm not aware of anyone who open carries though.
I've been told that top crimes on MI are tax evasion and identity theft.